1. Field of the Invention
The invention relates to a substrate, and more particularly, to a heat dissipation substrate requiring high thermal conductivity and a manufacturing method thereof.
2. Description of Related Art
Purposes of chip packaging are to provide a suitable signal path, a heat conduction path and a structure protection for a chip. Conventional wire bonding technique generally uses a leadframe to serve as a carrier of the chip. As the contact density of the chip gradually increases, the leadframe is no longer able to provide higher contact density, so that a package substrate having a high contact density is utilized to replace the leadframe, and the chip is packaged onto the package substrate through conductive media such as metal wires or bumps.
The package substrate is mainly formed by a metal substrate and a plurality of patterned conductive layers on the metal substrate and at least one insulating layer, wherein the insulating layer is disposed between two adjacent patterned conductive layers. Generally, an adhesion layer is disposed between the chip and the package substrate. The chip is fixed on the package substrate through the adhesion layer and is electrically connected to the package substrate, and heat generated by the chip can be conducted to the metal substrate through the adhesion layer, the patterned conductive layers and the insulating layer. However, since thermal conductivities of the adhesion layer and the insulating layer are relatively poor, when heat generated by the chip is conducted to the metal substrate through the adhesion layer and the insulating layer, a thermal resistance is increased, which may cause poor heat conduction. Therefore, efficiently conducting heat generated by the chip to the exterior is an issue of concern in the R&D for those designers.